when should we use " are waiting, and have been waiting"?

answer.. 1:plural pronoun(they,you,we etc)+verb+ing+...(it is present continuous tense) there are some fixed to be verb. (you+are,l+am) 2.it's present perfect continuous tense..(you can learn a lot of about tense by a English grammar)

***an English

"We are watching TV now" means at present the action of watching is going on... "We have been watching TV for 3 hours" means the action is going on from a specific time to till now.

when we say. ...We are waiting. ....It means .....hum intezaar kar rehe hai. ...par jab hum kehte hai. ...We have been waiting. .....iska matlab hum intezaar kar rehe hai (kab se )2 ghante se ya 3 ghante se....We have been waiting for 3 hours. .....