There are many signs on the songs, maybe we've never heard of them. signs will be discussed here that we rarely hear.
A tempo
a tempo : play the same speed when you start playing the song
Coda
coda : the final phrase of a song
D.S. al coda
should continue to the end of the song, back in 
marker, play up
From there, go to Coda, without any lag when moving around in the songs.
Fermata : last longer than usual. A silly but easy way to keep in mind that Fermata make a note which will be held approximately twice as long as usual.
legato :
itself has several different meanings, one based on the flow
of Italian music and the other based on the flow of German music. On the flow
of Italian, singing legato means a combination of several successive notes at a
time, while the German school to sing legato means as quickly as possible from
one note to the next tone without interruption at a time.
Oktaf, or 8va: play an octave higher or lower.
Poco
Poco : written before the words mean little.
Rit.
Ritardando : Often abbreviated as rit, played and gradually slows down.
Sforzando : play the notes of a sudden, very loud and clear.
Staccato : means to make a slow and separate records.
Tenuto mark : tap into the note, giving full value. Give emphasis additional notes by simply emphasizing the value of the count.
Tremolo : play the notes back and forth as fast as you can
