How to justify an application for research funding if the only cost is my own academic or intellectual labour (without any equipments) etc?
Now, the application form asks me to explain how I plan to use the funding. What would be the best way to respond to this question when I only incur the personal costs covering the time for my intellectual work?

Funding will cover x% of monthly salary costs for the PI, over the duration of the project. (The remaining y% will be funded by the PI's university to perform duties beyond the project scope.)

I only need to spend time reading related works, code a bit, and write a paper.

Those activities will require office space, IT equipment, etc. Those expenses can typically be included.