Can you spray something on the brakes for squeaking?

WD-40 but check your breaks before driving though

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You do not say what part of your breaks are squeaking. WD-40 is fine for the moving parts on the break assemble, but not on the block which makes contact with the rim of the wheel. If it is the break block, then it is caused by friction between the block and the rim. The blocks may be worn, if so replace both blocks.

It could also be that your break assembly is loose. I am assuming this is for a bicycle. If a motor vehicle then it may be that dust has accumulated inside the breaking assembly. The rim may also need re boring to allow the break block to make a better contact.