3 white wires & 3 black wires coming from ceiling box
The likely scenario is that the single white wire is the switched hot and the bundled white wires are the neutral. You need to confirm this.

With all wire bundles clear of each other and any metal, turn on the switch and then restore power at the breaker. With a non-contact tester, check the black wire bundle, the white wire bundle and the single white wire.

The black bundle should register hot. The white bundle should register not hot. The White wire should register hot.

Now turn off the switch (not the breaker) and check again. All should be the same except the white wire, which should now be not hot.

If that is the case, we have confirmed the setup.

Turn off the power at the breaker. Attach the white wire from the fixture to the white bundle. Attach the black fixture wire to the single wire. Attach the ground to the bare or green ground wire (if present) or to the metal box if no ground wire wire, or leave alone if no wire and a plastic box.

All should be well. If not, write back.

P.S. If this does work, the single white wire should have a black marking on it to show it is sometimes hot. Tape or a marker will do.