documentation is laaaaame; show me the page
Each OSM object will be one table row, each tag will be a column.
The tool can also generate Overpass queries for lists of OSM ids of objects (in the formw241112210,w148293046,w260133470,n1613997397). Mainly you'll paste a overpass query directly into the query field and hit run. The overpass query should only return tags to reduce API load on the endpoint. Also, be careful you don't accidentally recurse too far and fetch all nodes for a way, for example. The query out format must be json.
So a query like
[out:json] [timeout:25] ; ( node ["aerialway"] (51.648,10.647,51.668,10.685); way ["aerialway"] (51.648,10.647,51.668,10.685); relation ["aerialway"] (51.648,10.647,51.668,10.685); ); out tags;is recommended. "select specific columns" is only needed if you want to select a subset of columns. Normally all columns are contained in the output.