This is the 9116th most frequent Catalan word.
frega
Rub; friction.
Here, 'frega' is used as a noun referring to the action of scrubbing.
La frega a terra fa que el mosaic brilli.
The scrubbing on the floor makes the mosaic shine.
In this sentence, 'frega' is the third person singular of the verb 'fregar', meaning 'to scrub' or 'to clean'.
Quan frega els vidres, utilitza un producte especial.
When she cleans the windows, she uses a special product.
Here, 'frega' is part of a metaphorical expression, indicating that something is close to a figurative 'friction' or tension.