Every Revolut Business card can have a monthly limit set up which won't allow card holder spend more than the limit within a calendar month.
To check if your card has a monthly limit or to check how much is left, go to Cards and tap the card. If there's a limit set on it, you'll see a widget titled 'Spending limit' indicating your remaining allowance.
Account owner/admins can change this limit anytime. They can also link/unlink currency accounts to cards.
Note: remaining monthly limit tells you what's the theoretical maximum amount of money you can spend with that card. This is different from funds available which might be lower than that and may lead to 'insufficient balance' declines.