Looking to install Schuko power outlet in my Spanish home

[ACondusedPup]

Hey guys, I’m new to the forum and mainly here to seek help on something that is probably basic to most.

I have been replacing most of the in my home and it was mainly just 2 blue wires for an outlet. Basically I’ve noticed a few hubcaps around my house with wires inside them, but there are more than I imagined, and I’m not sure if I just take 2 of the blue wires and install it to the outlet I purchased.

I’ve attached some images below showing the hubs with the wires.

I would love some advice,
Thank you

 

[westward10]

Impossible to say as they look like joint boxes.

 

[ACondusedPup]

Impossible to say as they look like joint boxes.

How does that make it impossible to say if I may ask? Anything I can do to make it more easier to troubleshoot?

It was one of those “joint boxes” with less wires that I already installed a schuko outlet into previously. But obviously the one I shown in the pics above has way more wires.