I need to know this for my biology homework, it is the only definition I can’t find. So please help me out.
Another question, what is an R-group? This is in context with biology.
A beta-glycosidic linkage is one of two possible types of linkage between monosaccharides (simple sugars) in a disaccharide or polysaccharide. Your textbook should have a section on the structure of sugars – check it out. The term ‘R’ in R-group is just a placeholder for an unspecified organic (chemical) group.
Very last question. What are the uses of amino acids and proteins? I had 48 total questions and I couldn’t get these last three. Thanks to anyone who can help.
This question casts serious doubts on either your reading skills or your textbook. Amino acids and proteins are fundamental to the whole field of biology, much the way the fundamental particles are the foundation of particle physics. Name a complex organic compound and there’s a good chance of it being either a sugar or a protein of some kind.
Asking questions like these indicates that you really need research skills. A dictionary would be a good start here, as would dragging out an encyclopedia (any encyclopedia, even the most general-purpose ones will have something on proteins and amino acids).
I assure you that my reading skills are not lacking. This info is material that my prof discussed in class on Tuesday night. I was not able to attend due to a scholarchip meeting that I had at the same time. As for the encyclopedias, I am a college student, I cannot afford to shell out for a set of them. And last but not least, my book. The professors at Louisiana State University picked them out, everyone should have doubts about it. I do appreciate your help, but your sarcasm is not needed. Once again, thanks for the help.
College campuses usually have at least one building that holds numerous books, including encyclopedias. I suggest you make use of the facilities.
Believe it or not, I’m not trying to be sarcastic. I’m trying to give you the impetus to actually do something instead of expecting us to do everything. So you missed a lecture and can’t afford books. So you’re going to a college with crap texts. People have done more with less, I assure you. I think you can do it, if you just use your Internet connection (which I can assume a priori you have) to do the basic research. People are much more inclined to help you if you show you are willing to do the work.
So, why am I posting this? Because I think it can help you. That implies I think you are worth help. Please don’t prove that implicit assumption wrong.
How to Ask Questions the Smart Way – Eric S. Raymond gives a good account of what you can expect from technical fora (and GQ resembles one, even though it isn’t strictly a technical group), and how to get the most out of them. Think of it as a user’s manual to GQ, Usenet, and all places where you can ask questions and get factual answers. With a bit of tweaking, it can apply to college profs just as well. 
Sorry if I was a bit short tempered with you earlier. It has been a long day and I was in a bad mood. I know that that is a no excuse, but I am sorry. Thanks again for the help and for the constructive criticism.
“What is a beta glycosidic linkage?”
This has been answered by JHW, so I won’t repeat the answer, but I’ll make it easier for you to find answers like this in the future.
Glycosidic is the adjective of glycoside, a generic term for “sugar”. Looking up glycoside or sugar in the index of your textbook will likely have yielded the answer.
“Another question, what is an R-group? This is in context with biology.”
The R-group in chemistry stands for any (typically carbon-containing) group. In biology, it is often used to refer to an unspecified amino acid side chain.
“What are the uses of amino acids and proteins?”
Amino acids are used to build proteins. Proteins provide structure in some cases (such as actin and myosin in muscle tissue), and act as catalysts in some cases (such as beta-galactosidase or proteases).
Your textbook should have a chapter (or several chapters) on amino acids and proteins.