Git has a concept called as tree-ish it means something that is part of tree or reference to tree. Tree in git means nothing but the structure of commits. These commits contains the information like Sha-1, date, author, comments and changes.
We are able reference our commit by using full or shorten SHA-1 hash, ancestry or HEAD pointer.
for e.g.:- this will point to the tip of the current checkedout branch i.e. HEAD
git ls-tree HEAD
This returns list of files at that point. May also use branch name instea of HEAD.
git ls-tree master
Also can see particular dirctory within the branch
git ls-tree master directoryname