A notice asking who out there could do some future work. There is nothing to win yet. Responding with a short capability statement puts your name in front of the buyer early, and if enough small businesses respond, the agency may set the eventual contract aside for small business.

In a sentence

"This is a sources sought notice for market research purposes only; no solicitation exists at this time." Translation: the contract is not real yet, but the audience list is being written now.