Ok. I highly recommend this guy's videos on how to flyfish for bass https://www.youtube.com/playlist?list=PLlXEim6I9OMWMvcpEwQhxfJxrPsBk2uce
Ok. So in bait fishing, the line is really light and the bait or lure is heavy. So you use the weight of the bait to load your rod and fling your bait out into the water.
In fly fishing the flies are generally really light, so the weight comes from the fly line. Thats why fly rods are longer than spinning rods.
A fly line is fairly thick, a few millimeters, but fish arent that dumb, so you cant tie your fly on the the fly line, they can see it.
So you need monofilament to be sneaky.
The first type of monofilament that you attach directly to the fly line with a knot is a leader. A leader is a piece of tapered monofilament. It is thick at the fly line end and thinner at rhe other end. It helps with the physics of loading the fly rod and turning over the line. Leaders come in packages of 1-3, and come in a few lengths. Generally speaking, the shorter leaders are easier to cast.
Then you'll need tippet. Tippet is also monofilament, it is one thickness along it's whole length. It comes in spools. Tippet is used basically to protect your leader, so as you change flies you dont lose a lot of leader material.
Both the tippet and leader work on an x stystem for sizing. 7 x -0x. 7x is a very thin leader. Each tippet is thicker as you go towards 0. After 0 they are in pound test, such as 5 lb, 10 lb and so on.
Leader material- RIO Products Leaders Bass Leaders 9' 8Lb 3 Pack, Clear https://www.amazon.com/dp/B0160BRIO8/ref=cm_sw_r_cp_api_i_8vufFb7N8NVW4
Tippet-Rio Bass Fly Fishing Tippet 3 Pack https://www.amazon.com/dp/B06Y2GJ26X/ref=cm_sw_r_cp_api_i_XwufFbEC6HQ1H
You will need to learn a few knots to tie your leader and tippet-
Here are some knot tutorials, plus this guy is really good at explaining stuff https://www.youtube.com/playlist?list=RDCMUC8J2w-RuMBJz-aLAyJyluBw&feature=share&playnext=1
I also recommend this channel- https://www.youtube.com/c/thenewflyfishertv
I know this is a lot. This is a wondeful hobby, but it has a tough entry point. Good luck. Reach out with questions, and post your first fish back here later.
Take care.