This is small list of Korean you can expect to hear in a normal training session.
Attention = Charyot
Classification of Assistant Instructor (1st to 3rd degree) = Boo-Sabum, Nim Geh
Classification of Instructor/International Instructor = Sabum, Nim Geh
Bow = Kyong – Ye
Commence/Start = Si Jak
Ready = Junbi
Stop = Goman (or Hecho Separate)
Return to Ready Stance = Baro
About Turn = Dwiyo Torra
Left = Wen
Right = Oran
Training Room = Dojang
Training Suit = Dobok
One = Hana
Two = Dool
Three = Set
Four = Net
Five = Tasot
Six = Yaset
Seven = Ilgop
Eight = Yadul
Nine = Ahop
Ten = Yul
Blue and Red in competitions are called Hong(red) Chong(blue).
Other Korean terminology can be found in your belt grading syllabus once you register as a student.