Unsettled funds in your account represent the funds you expect to receive from profits made or stocks sold. Settlement for trades is not instant, and exchanges follow a rolling settlement cycle.
Even if you sell stocks or make intraday profits, you cannot immediately use the proceeds to purchase other shares. The funds from your sale proceeds get settled in your trading account after one trading day. Additionally, if the T+1 day coincides with a settlement holiday, your profits will be available on the next trade settlement day.