it`s a comparison between two musical notes.
In piano music, a simile indicates that the player should continue to perform in the same manner as previously directed, usually in terms of dynamics or articulation. It is a direction to maintain the same style or approach in playing the piece.
The music gets louder
The simile music symbol in musical notation indicates that the previous section of music should be repeated.
pianissimo!
slowly!
Slow
In musical terms, rinforzando means reinforced.
That's not a standard term in music.
Play loudly!
personification and simile
Simile
similes