Symbols in choir

1. What does this symbol mean in choir?
2. What do we call these symbols in music?

What does this symbol mean in choir?

The two main dynamic symbols are f (forte), which means loud and p (piano), which means soft. ... Two more symbols are created by doubling the letters to make the dynamic more extreme (ff - very loud, pp - very soft).

What do we call these symbols in music?

In musical notation, the sharp (♯), flat (♭), and natural (♮) symbols, among others, are used to mark such notes, and those symbols may themselves be called accidentals.