You are expecting it to work like in MS-DOS, however, this is linux.

Wildcards in linux are expanded by your shell to match all items fitting the wildcards. ls does not see your wildcard. It only sees a list of file and directory names matching the wildcard. So it will show the contents of all items listed, i.e., the name of a file or the contents of a folder. In MS-DOS, wildcards would cause the dir command itself to filter the list to list only names fitting the wildcard.

To filter the output of ls, e.g., to only see file and folder names matching f*, use grep, i.e., pipe the output of ls into grep like:

ls | grep ^f.*

^ and .* are regular expressions. ^f means: f but only at the very start. .* means . any character * any number of times.