how to make a cell only except negative’s numbers

There is no data validation in Numbers but you can do one of a few things.

1) Format the cell as a slider or slider with a minimum value that is negative, a maximum of 0, and an increment size that suits what you need (10, 1, 0.1, 0.01, or whatever). If a positive number is typed into the cell, it will set it to 0. You can use the slider/stepper to change the value vs typing into the cell if the range is reasonable. Too large of a range makes the slider/stepper mechanism impossible to use.

2) Set up a custom format that displays positive numbers with a negative sign in front of them so they look like they are negative. The value in the cell will be positive but it will display as negative. In the formulas that use those numbers, turn them into negative.