What each screen is for

Set-up (once)

Funders	The agency that gives the money, the program it runs, and the fiscal year it uses.
Categories	The buckets spending is coded to. Money rolls up the tree, so a rule like “60% food” has something to measure.
Entities	The people and vehicles you pay. One entity can have several engagements, which keeps a shared salary from being counted twice.

Planning the money

Budgets	What you intend to spend. A proposal plans against a program before the contract exists; an approved budget is the frozen envelope for one contract, and is what actual spending is measured against.
What-ifs	A what-if copies an existing budget so you can test a change — “what if we hired a second driver?” — without touching the approved numbers. Promote it if the idea is accepted; discard it otherwise.

Contracts and costs

Awards	Your contracts. Each one holds its funding slices (the money available for a date range), its spending rules, and any budgets planned against it.
Sinks	The ongoing costs grant money pays for: a truck lease, a salary, a storage rental. Each is funded by one or more contract slices.

Day to day

Spend	Record an invoice against a cost and the slice that pays for it.
Usage	Log miles, gallons or hours — usually before the bill arrives, which is expected.
Periods	Reporting cadence and month-end close.

Checking

Compliance	Every contract's rules against actual spending, for a fiscal year or a reporting period.
Period report	Spend and usage for one reporting period.
Data health	Anything that looks wrong, ranked, with the screen that fixes it.

Power tools

Raw tables	A direct view of every table, for edge cases the screens do not cover. Nothing in the normal workflow sends you here.
JSON API	The same data over HTTP, for scripting or bulk loads.