What does "take 4 tablets twice a day" mean?

[BeBopALuIa]

I'm on 250mg antibiotics (phenoxymethylpenicillin). I'm reading it as take 8 tablets a day but surely that can't be right?

It can be either way. Here’s the British national formularies advice on dosing for sore throat:
Adults:
500 mg 4 times a day, alternatively 1000 mg twice daily for 5–10 days.

The NHS link I posted above is perfectly clear.

It’s clear but incomplete. The OP needs to check with her prescriber if unsure given that 4 tablets twice a day is a correct dose for some indications.