The Floor Price denotes the minimum price threshold at which investors can place their bids for shares during an Offer For Sale (OFS). The entities selling the shares, often the company's promoters or large shareholders, declare this floor price either one day (T-1 day) or two days (T-2 days) ahead of the OFS commencement date.
If you're interested in understanding how to apply for an OFS, we recommend referring to this article.