r symbol what is this ? how to understand the meaning of all signal like mp, mf , Z, R, ......Rall.. ?

reinforced?
The rinforzando ("reinforced," rfz or rf) implies more of a "leaning on" the note such that it emerges from the texture or becomes the high point of the phrase, but not harshly.
The subito forte ("suddenly strong," sf) indicates that the note is to stick out from the preceding and following notes
https://www.quora.com/Music-Theory-What-is-the-difference-between-sf-rf…