What is a free float in a share market?

Let's say a company has 70% as promotor shares, this makes 30% shares are considered free float shares.

Higher the number of free float shares, higher is the volatility and volume available for free trade.

Source and further reads:

 https://economictimes.indiatimes.com/markets/stocks/news/free-float-market-capitalisation-determines-index-weightage/articleshow/58178327.cms