Unfortunately, can't view the attached image -- some SQL error. But if you're talking about the column with the icon that looks sorta like a refresh icon (two green arrows in a circle), that's the quantity you want to list as available for trade.
The column with the gold star is your wishlist count, and the column with the Deckbox icon is how many you need for your deck. If you don't see those columns, they can be shown or hidden using the Columns dropdown.
I'm assuming you're on mobile, because on desktop, all those icons have hover tooltips that explain what they mean. No easy way to see the tooltips on mobile, sadly. You just see them briefly when you tap the icon to sort by that column, but then the page reloads! Argh
Welcome to Deckbox, and more importantly, welcome to MTG!