This is the amount that is available to fund into your cards out of the total money that was funded into your pool account. When you fund a card in a budget, there is a deduction from "Available to assign" and is appended into "Available to spend"

This is the sum of all the amount in your cards, which has been funded from the budgets (some of all "Available to spend" across all cards in every budget). When you fund a card in a budget, there is a deduction from "Available to assign" and is appended into "Available to spend"

Total pool value

This is the total fund you have with Volopay available to be spent on your expenses. This is the sum of all the amount in your cards ("Available to spend") and the amount that is available to be funded ("Available to Assign") into your cards.