With invoice finance, a lender advances most of an invoice's value (often 80–90%) straight away and the rest, minus fees, when the client pays. "Factoring" means the lender also collects the debt; "invoice discounting" means you still chase it yourself.
It helps cash flow but is not cheap, and fees reduce your margin on every invoice. Chasing late payers effectively is usually the first thing to fix.
Example
A £5,000 invoice is financed: £4,250 now, the balance less a £150 fee when the client pays.