Open a piano piece and you can find any number of piano symbols, words, and abbreviations. The composer included them to help you know how he envisioned the piece being playedand how it will sound the best to be performed. Consequently, it is wise to know what the musical terms mean and to be able to instantly identify them.
Dynamic markings tell how quietly or loudly to play
pp
Pianissimo: very soft
p
Piano: soft
MP
Mezzo piano: moderately soft. Mezzo means moderately in Italian. Anything with mezzo written before it means moderately.
MP
Mezzo forte: moderately loud
F
Forte: loud
ff
Fortissimo: very loud

Crescendo: sometimes written out, abbreviated to cresc., or written as a marking. Play gradually louder

Diminuendo: sometimes written out or as decrescendo, or abbreviated as decresc., or written as a marking. Play gradually softer
Tempo markings tell the pace (or speed) which are to play
The tempo is usually marked at the top of the piano piece, before you begin. Sometimes songs will change tempo in middle of the song. The composer will write when to change the speed. There are not any special markings for the tempo the word is just written out.
Adagio
Adagio: slowly
Andante
Andante: walking speed
Moderato
Moderato: moderate tempo
Allegretto
Allegretto: rather fast
Allegro
Allegro: fast and lively, cheerfully
Vivace
Vivace: very fast
Various markings: There are numerous other markings throughout a song. These are some of the more common.
A tempo
a tempo: play the same speed as when you started the song
Coda
coda: the ending phrases of a song
D.S. al coda
D.S. al coda: stands for DalSegno al Coda. Instead of continuing to the end of the song, return to the
marking, play until the 


From there, immediately go to the Coda, without any pauses while moving around in the song.

Fermata: fermata, fermata, hold it longer than you should be. A silly but easy way to remember that the fermata makes a note to be held about twice as long as it usually is.

Legato: sometimes legato is written out, but often it is represented by a slur. Play the notes smoothly and connected.

Poco
Poco: written before any words means a little
Rit.
Ritardando: often abbreviated to rit., it means to gradually slow down

Sforzando: play the notes suddenly, very loud and forcefully

Staccato: the dot means to make the note jumpy and detached

Staccato: the dot means to make the note jumpy and detached

Tenuto mark: press into the note, giving it its full value. Give the note extra emphasis by simply stressing the its count value

Tremolo: play the notes back and forth as rapidly as you can
Yoke Wong recommends theEasy Beginner Piano Course