How do you find out what conferences are in your field? I’m new to the culture of research and my professor suggested that I try to submit an abstract to a conference. The only problem is, I have no idea how you figure out what type of conferences there are. I’m wondering if there’s some type of conference portal that lists them all in different fields...? 

There’s so many conferences out there and I’m just curious how one could go about finding conferences to submit to. I should say, I’m not asking what conferences I should submit to, but how you figure out which conferences even exist in the first place.
Another thing that you should do, and it will help with this issue is to join a professional organization in your field. I'll guess that most fields have one or more such organizations, and I'll also guess that most of those have a special rate structure for students. This is true in Mathematics and Computer Science, for example (each of which as two or more such). The ACM (in CS) also has Special Interest Groups (SIGS) for subfields that you can join. 

And then, the problem will go away as your email inbox will be full of announcements. Likewise, the "journal" that is distributed to all members will also be full of announcements of conferences, even those not formally sponsored by the organization. The SIGS will also send you lots of enticing ads. 

But, you should probably join for a lot of reasons, not just the email "enhancements". 

And, of course, those same societies normally have web sites, and their conferences are usually promoted there. They are likely to be some of the top conferences in that field.