Reading music is a skill, not a secret code. Like reading words, it starts with recognizing a few symbols and gradually becomes automatic. You do not need to learn it all before you play — you learn it by using it.
The two things that matter first
Almost everything on a page of music answers one of two questions: which note and how long. The staff lines tell you the pitch, and the note shapes tell you the rhythm. Focus on those two ideas and the rest fills in naturally.
Treble and bass together
Piano uses two staves joined together. Your right hand generally reads the upper (treble) staff and your left hand reads the lower (bass) staff. You will be surprised how quickly your eyes learn to track both lines at once.
Read slowly, out loud
Say the note names out loud as you play them, at a snail's pace. Saying and playing at the same time is slow at first, but it builds a much stronger connection than guessing your way through.