Just like the language of aviation is English, the language of music is Latin. Here are some terms that should keep you covered about 99% of the time (selected and edited from wikipedia):

Two different kinds of articulation:

• staccato: making each note brief and detached; the opposite of legato
• legato: joined; i.e., smoothly, in a connected manner

Four different ways to talk about tempo:

• accelerando, accel.: accelerating; gradually increasing the tempo
• ritardando, often said simply ritard., rit.: slowing down; decelerating; opposite of accelerando
• rubato: i.e., flexible in tempo, applied to notes within a musical phrase for expressive effect
• a tempo: in time; i.e., the performer should return to the main tempo of the piece (after an accelerando or ritardando)

Six different levels of volume:

• pianissimo or pp : very gently; i.e., perform very softly, even softer than piano.
• piano or p: gently, softly
• mezzo piano or mp: half softly; i.e., moderately softly.
• mezzo forte or mf: half loudly; i.e., moderately loudly.
• forte or f: strong, loudly
• fortissimo or ff: very loud

And finally, two different ways to change your volume:

• crescendo: growing; i.e., progressively louder (contrast decrescendo)
• decrescendo: decreasing in loudness; i.e., progressively softer

If you know these – you’ve got the basics!