That doesn't sound dumb at all, we all have to learn sometime!
A sucker is typically an undesired offshoot from the main tree
. You'll often find them near the ground (sometime it looks like they are growing
directly out of the ground) but sometimes they are up on the trunk a bit and they look like a young misplaced branch that is just sucking onto the main tree
. They'll also typically be smaller than an inch in diameter. You can look at just about any tree
out in the world and see suckers everywhere, and now that you know what to look fo you'll see them everywhere.
Usually they are undesired due to strange growth locations and they'll mess up to look of your tree
in the short term, but if you are inclined to start an entirely new tree
they work great! Good luck!