Wiring – 17 light mason jar chandelier

If the device was wired using French conventions, the ground is yellow, blue is the neutral wire, and brown is the live wire (ref).

That said, the ground should be apparent by inspection. Look at where the yellow (or green and yellow) wire goes. It surely is attached directly to metal on the chandelier.

As for the other two wires, it doesn't matter electrically which is which: a/c (alternating current) works forwards and backwards the same. :-) For electrical safety reasons, it is best to get them right. That way if one unscrews a bulb while power is applied, it is harder to get a shock: The power will be at the bottom of the socket. With neutral and live reversed, the sides of the socket is energized relative to ground, so a casual bulb-swapper could get shocked.

There may be an in-ceiling connector as well as the connections which are certainly in the tape, but if you cannot pull a connector down by gently pulling on the wires, and if you cannot access the ceiling space, then the following will work.

(1) BEST: Get somebody competent to assist or to do the job - you have less chance of dying that way.

Otherwise:
(2) The red and white wires provide power. Presumably this is AC mains - you did not say what the supply is but if the bulbs are 110V or 230V rated then mains AC is what is involved.

Mains voltage is, of course, capable of delivering a lethal shock - I know you know that but a reminder does not hurt.

Connection is made to the blue and brown wires inside the tape. If the person who did it was half competent they will have used a very compact joiner or will have soldered the wires together, but it is likely that they are just twisted together.

Ensure life insurance is up to date.
Ensure house insurance is up to date and that you are prepared to accept the worst case outcomes - eg house burned down, You or others dead.(Unlikey, but always be aware).
Then.

Turn light off then on with usual switch - now you know the switch works.
Leave the light ON.

Turn off circuit to light at switchboard so light goes out.
ie Turn off circuit breaker or remove relevant fuse. Light is now OFF.

NOW turn off light at usual switch.
You now have two off switches. in series.

Tell everyone to not switch ANY light switches or power points. Your life just may depend on this.

Assume that there is AC mains power at light - there MAY be.
I have experienced AC mains present on a light socket under the conditions described above. Really!

Remove tape, assuming that either wire MAY be alive.
Red wire should be most likely to be live / Phase BUT no guarantee.

If wires are twisted together pull apart.
If a connector is used, discoinnect.
If soldered, unsolder or cut wires near to join in a manner which will allow you to rejoining OK. Using a connector - even a screw down "chocolate block" is preferred when reassembling. There is ample room for it in the ceiling space shown.

The unconnected green and yellow wire is for the earth wire that the lamp manufacturer thought that you should use but which the wiring person decided you did not need.

IF soldering with an earthed soldering iron be aware that either wire COULD have mains voltage potential relative to earth.

Option (1) should be loooking more attractive.

Report back - inquiring minds want to know.