“Have you heard back about the lease yet?”
You want to renew the lease on your apartment. Your husband has sent an email to the landlord, but you don't know if she responded to him yet. You ask him this.
Have you heard back about the lease yet?
have you (done something) yet?
You ask this when you expect someone to do something and want to check whether it's been done:
Have you paid the rent yet?
You also use this when you expect something to happen to someone:
Everyone around here is getting sick. Have you caught it yet?
This means to get a response from someone to a question or request. You can also express the person who is responding to you with the word "from":
Have you heard back from the landlord yet?