Here is explanation about Discovered Check:
Discovered check happens when one piece moved and after moving that piece the attack of anther piece touches the king it is discovered check.
Discovered Check could be happend and result maximum 2 checks Suppose an empty Chess board and if my enemy's black king on E file on E8 square and my white rook is on E1 and white bishop is on E2 then if i move my white bishop to H5 square now note the situation
My bishop is attacking from H5 square to my enemy king
My rook's way is cleared now and rook now attacking from E1 square.
this is one illustration of Discovered check many other possibilities could happen in game.
You could play with me on Chess.com my username is hasanbadshah :)
remember two rooks can never create a discovered check.
but queen+rook can create it would be like of rook move and check, which result cleared the queen's way which also threatening the enemy king so it is discovered.
If any confusion u have feel free to post.