Bell peppers are fruits rather than vegetables although for culinary purposes, they are treated as vegetables. And they aren’t really peppers. Capsicum is the proper name; the Spanish call them pimientos. In everyday cooking language, however, pimientos have become more associated with the smaller, sweeter varieties of bell pepper.
Confusing? Never mind. So long as you know what they look like. This isn’t about the bell pepper, anyway, but how to prepare them for cooking.

Start by cutting off the top. That means the handle and a small section of the body so that what you cut off looks like a pan cover.
Stand the bell pepper on a cutting board, cut side down. Cut off the flesh, from the top going down, avoiding the seeds and the membranes.

Turn the bell pepper around as you cut until only the seeds and membranes remain.

Now, take the flesh and cut into whatever shape and size the recipe requires. Fine dice? Cut into strips then cut the strips perpendicularly to get small pieces.
What’s the big deal about bell peppers? I made a salsa that includes bell peppers.
Recipes with bell peppers: