What is it called when you try to play a song for the first time by reading the sheet music?

When you try to play a song for the first time by reading the sheet music, it is called sight-reading or sight-playing.

When you try to play a song for the first time by reading the sheet music, it is called sight-reading. Sight-reading involves interpreting and performing a piece of music in real-time, without any prior rehearsal or practice. It requires the musician to read the notation on the sheet music and translate it into the appropriate notes, rhythm, dynamics, and expression while playing the instrument.