Why is there mould on my outside bricks?

[Yohohaha]

Has it just been damp for too long due to winter? Or do I have a bigger problem? This is the wall behind the kitchen.

I think it’s efflorescence/ salts rather than mould.

That isn't mould it's salts.
I've tried scrubbing it off my bricks but it won't budge

www.idealresponse.co.uk/blog/efflorescence-the-salty-deposits-affecting-your-property/

Ok thank you! I though it was mould as it's fluffy rather than salty looking!

That's a lot of salt! Are the bricks new?
I'm no expert and our house suffers too but things to think about:
Is the water patches going over your damp course and is there a leak inside kitchen or from roof gutters? Could lead to more problems if so.
As I say we are suffering too

Looks like you have a water leak probably from a pipe. Stand back and take a wider pic. Your wet patch is hill-shaped. The source of water is probably at the centre of the hill. Is the room a kitchen or bathroom? Is there a washing machine or garden tap? If it was ground water it would be more level all along the wall.

It can also be caused from a drip from above but I don't see signs of that.

When you have repaired the source of water and it has dried, you can brush off the crystals with a stiff dry brush. Do not try to wash them off with water. Do not use a wire brush or a scraper as you will damagd the bricks.

It will weather away naturally in a few years.

Do not allow anyone who sells silicone injections into your house.