I’m not sure who made the joke that Mexican food is just the same five ingredients arranged in different ways, but it’s pretty true.
You’re familiar with the basic idea of tacos and burritos from Taco Bell, so I’ll give you the intermediate-level course.
Enchiladas – soft corn tortillas (not the crunchy ones that tacos are in) with various fillings, cooked in a (usually) red sauce. If it’s any other kind of sauce, the menu will mention it–the main alternative you’ll usually see is a green sauce, made from tomatillos, which is a bit more tangy.
Tamales – soft cornmeal, kinda like polenta, with a meat filling, wrapped in a corn husk and steamed. I didn’t have one of these until I was about 28, and damn, was I missing out. You don’t eat the corn husk, just open it and eat the innards.
Chimichanga – Same as a burrito, only dropped in the deep fryer. Terribly fattening, but pretty damned delicious.
Tostadas – flat tortilla with various toppings. Similar to the Mexican pizza from Taco Bell, but with more stuff on it.
Flautas/Taquitos – Deep fried corn tortilla rolled into a small tube, filled with beef or chicken.
Carnitas – Pork, slow-cooked in spices and its own fat, so it’s an odd combination of slow-cooked and deep-fried. More yummy than I’m making it sound.
Mole – Spice blend made of ground chiles and cocoa powder. Pronounced like saying the word mole and then the letter A. Mole-A.
Quesadilla – Flour tortilla, folded in half and filled with cheese, meat, and possibly onions and green peppers, then grilled until the cheese melts and cut into triangles.
Chorizo – Very greasy, lightly spicy pork sausage with a reddish hue. Delicious with eggs (huevos con chorizo).
Most Mexican places will have combination platters that give you one of several things on this list. You may want to try one of those. Quesadillas are good for newbies, as are enchiladas or chimichangas.