Definition
To keep something to a specified number or amount means ensuring it does not exceed that limit.
將…局限在（特定數量）之內
He ensures that the company’s expenses are kept to the budget.
他確保公司的開支控制在預算之內。
We need to keep the number of people at the meeting to ten.
我們需要將會議人數控制在十人以內。
To manage costs, they decided to keep the project budget to five thousand dollars.
為了控制成本，他們決定將項目預算控制在五千美元以內。