Having the reds in an unenclosed metallic connector is very dangerous, as all of them are permanently live!!!!!!!!! So that needs correcting before anything!
So you have the 3 red that is a LIVE loop. And they stay together in an INSULATED connector.(this is not directly connected to any terminal on the fitting, some do have a spare terminal, but most do not, so an insulated terminal block that can contain all three cores is required).
The unsleeved black should be the neutral, but I did not install it so that is an assumption without testing it.
The yellow sleeved black would suggest this is a a switch line, but I would expect this to be sleeved red.
And the greens are your CPCs (AKA earth)
So on your light fitting if you only have live, neutral and earth terminals you do this. 1) All 3 reds into a separate insulated connector together as a live loop 2) Yellow sleeved black into the live terminal as a switch line 3) All Unsleeved blacks into the neutral terminal as a neutral 4) All greens sleeved conductors into the earth terminal as your CPC loop.
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