Subject decisions

So far I have 5 alevels, but one is native language, the other four are further math, math, business, and economics. I am a bit afraid if I fail further math, will it have much negative consequences on my application if I failed my further maths? (Further math is not required for my current offers)

It could potentially have negative consequences if you do fail further maths

Can I ask what is the negative consequences likely to be?

So far I have 5 alevels, but one is native language, the other four are further math, math, business, and economics. I am a bit afraid if I fail further math, will it have much negative consequences on my application if I failed my further maths? (Further math is not required for my current offers)

Why don’t you drop business? It’s not respected when you’re doing it alongside economics and 5 a levels is far too many . If you want to study maths or economics at university doing economics and business adds nothing to your application but further maths either boosts your application (for economics) or is necessary (for maths).

A bit late to the thread but hopefully this would help you:
If you are considering a competitive university (like Oxbridge, Imperial, UCL, LSE, or - something like that basically), they don't tend to accept your native language A Level (you are expected to get A/A* if you are native as the specification is designed for students whose that language is a second language), so I would say don't bother studying it unless you have time.
In terms of further math, speak to your college - see if they allow you to do an AS before going onto a full A Level, some may allow you to drop it after taking the AS in the first year so it'll still worth some amount of UCAS Tariff Points while not ruining your overall A Level result, but some do not. I'd say, if you are uncertain about further math, do an AS before thinking not taking it.
P.S. Even if you do fail the subject, you have to put that on your UCAS application according to the rules.