Lots of people are pointing out that Rfc1 wins you c7, but this is proof of more general advice
Employ Zwischenzug where possible
Zwischenzug mean "intermediate move"; it's the idea of placing your opponent in more pressure before making an obvious move.
The most clear examples involve being in a position to take an opposing piece, lets say a rook. Instead of taking it right away, you might be able to put your opponent in check first, developing a piece. Then, after your opponent has answered the more pressing concern of check, now you can go ahead and take their rook.
In this example, you've pinned black's queen. Nice work. Now, there's no immediate move black has to get out of it. You could go ahead and take black's queen, black captures back, then you play on like usual.
Instead, what Stockfish is proposing is that you place black in a more uncomfortable position before making the trade. There are only a few responses to Rfc7; none of them are very good for black. So why not go ahead and force one of those "not very good moves", especially if it lets you develop a rook? The queen exchange isn't going anywhere, and you can use it to leverage an even larger advantage.
"To take is a mistake"
Now, that's one of those over-generalized "rules" which only applies in certain cases, but this is one of them!
The idea is that you never want to sacrifice the momentum or positioning gained in an exchange if you don't have to, and often, the person initiating an exchange loses both of those.
I'm obviously not saying that taking a piece is always (or even usually) bad; if black's queen weren't pinned, you should obviously capture it. But right now, you don't have to take it. It's not going anywhere. Consider these outcomes:
You take the queen and black recaptures with their rook, threatening white's bishop. Now white can move their bishop to d3, which encourages black to play g6, or they can move their bishop elsewhere, encouraging Rhd8. So now black's either developed a rook and strengthened their king-side pawns, or developed a battery on a semi-open file. In exchange, white's lost development on their bishop.
White should still win on material, but they didn't have to give black that positional advantage. If white moves Rfc7, then black captures the queen, white recaptures with their rook. The queens are off the board and white developed a rook; advantage white.
Of course, if black doesn't make the trade you've still got the advantage, and if black removes the pin on their queen, you can just grab it then.
Qxd6 says "I'm trading queens because I'm up on material", but Rfc7 says to black "You can initiate the trade and I'll develop a rook for it, or you can squirm a little first and I'll do it when I'm ready."