For "to be" in the present tense, you use the verb "เป็น" (pen) which can be translated as "to be" or "is/are".
Examples:
* You are a student.
คุณเป็นนักเรียน (khun pen nak rian)
* We are friends.
เราเป็นเพื่อนกัน (rao pen phooen gan)
However, "are" can also be part of a verb phrase. In these cases, you might use a different word.
For example:
* You are eating.
คุณกำลังกิน (khun gamlang gin) - "กำลัง" (gamlang) indicates a continuous action
* They are working.
พวกเขากำลังทำงาน (phueak khao gamlang tham ngaan) - "กำลัง" (gamlang) indicates a continuous action
Let me know if you want to say "are" in a specific context and I can help you find the right translation.