I couldn't find anywhere what are the meanings of the columns at the Sense site for "GET _cat/indices" (indices endpoint).
If i'll try to guess -
yellow open .marvel-kibana 1 1 1 0 3.1kb 3.1kb
[status] [some other status?] [index name] [shards?] [?] [num of docs] [??] [size] [actual size?]