What kind of wire this is in my ceilling
Prior to RG6 being adopted RG 58/59 were common for data (cable tv) most places were updated with RG6 because it is better with modern cable bandwidths. 3 white round cables that were replaced by 3 black round cables, not power most probably RG6 the cable has it’s type and MFG stamped on the side at regular intervals as others have mentioned.