"Used for stocks/F&O" refers to the funds blocked against orders you've placed for that day. It shows the amount already used for trading. Once settled, this will appear under "All transactions".
The total amount used for trades on T day will be visible under "Used Balance".
At the end of T day, refer to the "All Transactions" tab or the contract note sent to your email. Alternatively, you can download it yourself from the "All Transactions" tab by selecting the day and clicking the download option in the top right-hand corner.
Note: T day means transaction day.