My Gemini wireman:
(Kalau kaboom not my fault sue Google, sekadar post as a joke not real advice)

Based on the photos provided, you are replacing an old 3-gang wall switch with a new 3-gang switch.

⚠️ WARNING: DANGER OF ELECTROCUTION
Before doing anything, go to your fuse box/consumer unit and turn off the main power or the specific breaker for the lighting circuit. Do not touch any wires until you are sure the power is off.

Step 1: Understand the Wiring
The Old Switch (Top):

The "Loop" (Live In): Notice the short red wires "jumping" from one switch module to the next? That is carrying the power (Live) to all three buttons. The wire coming from the wall that feeds this loop is your LIVE IN.

The Outputs (Switched Live): There are 3 distinct wires (two red, one blue) leaving the individual switch modules. These go to your lights/fans.

The New Switch (Bottom):

L: This is the Common Input (Live In).

L1, L2, L3: These are the outputs to your three different lights.

Note: Your new switch appears to have an internal bridge (one single "L" terminal for all three switches), which means you do not need the messy jumper wires from the old switch.

Step 2: Wiring Instructions

Here is exactly where each wire goes:

Identify the Main Live Wire: On the old switch, find the red wire coming from the wall that connects to the "jumper loop" (it looks like it's connected to the top switch's center terminal).

Action: Remove this wire and connect it to the terminal marked L on the new switch. (Discard the short jumper loops; the new switch doesn't likely need them).

Connect the Lights (The Outputs):

Take the wire connected to the Top switch output on the old unit. Connect it to L1 on the new switch.

Take the wire connected to the Bottom Left switch output on the old unit. Connect it to L2 on the new switch.

Take the wire (the blue one) connected to the Bottom Right switch output on the old unit. Connect it to L3 on the new switch.

The Yellow Wire (Earth):

You have a yellow wire loose in the wall box. This is the Earth wire.

If the new switch has a metal terminal marked with the Earth symbol (⏚), connect the yellow wire to it.

If the new switch is all plastic and has no Earth terminal, wrap the exposed copper end of the yellow wire with electrical tape to make it safe and tuck it into the back of the box.

Summary of Connections
Red (Source from wall) →→ L
Red (Light 1) →→ L1
Red (Light 2) →→ L2
Blue (Light 3) →→ L3

Step 3: Finish Up
Double-check that all screws are tight and no loose copper wire is visible outside the holes.
Screw the new switch plate into the wall box.
Turn the power back on and test the buttons.

Note: If you find that only one button works after installation, the new switch might not be internally bridged. If that happens, you would need to use short wires to bridge the "L" terminals together, but looking at your photo, the single large "L" suggests you don't need to do this.