Could you guys tell me which one is correct?
- We are having an open house.
- We are holding an open house?
Could you guys tell me which one is correct?
Both are correct. "Having" and "holding" apply to events in general -- an open house, a party, a lecture, etc. "Hold" is usually limited to events where the subject has some role greater than attendee -- you and I may have a meeting, but you (as host) hold an open house. Or have; that's not incorrect.
They are both correct.
"have" is correct in multiple definitions of the word, such as to allow or experience, etc.
"hold" is correct using this meaning of the word:
to hold: to assemble for and carry on the activity of (held a convention); to produce or sponsor especially as a public exhibition (will hold an art show)