Installing a celling light with 2 black and 1 yellow wire
Do you have a volt meter or a way to detect which of the lines have power?
In my area one of the blacks would be hot but having 3 wires is unusual.
a switched hot goes to the brown wire or L terminal.
The neutral goes to the blue or n terminal.
I would check with a meter to see where there is voltage.
black to black?
then voltage black to yellow?
Last the other black to yellow 0 volts?
I was giving an example as 3 wires would not be normal with 2 the same color if you could take some measurements it would be helpful.
I have seen black as the hot and neutral depending on country.
If you could describe the wires coming in the box I can’t make them out clearly which ones are together etc
No one has answered probably because there is not enough information.