Git pull aborts itself, local file changes will be overwritten by merge -

i have changed file friend working @ same time. did changes , want push says should pull first. when git pull, says:

error: local changes following files overwritten merge: please, commit changes or stash them before can merge.
aborting

how can merge file? if file friend change? sure has added stuff , have added stuff. how our changes handled?

one approach commit file first pull.

git add filename git commit  //enter commit message , save  git pull  

another approach stash changes pull. apply stash.

git stash git pull git stash apply stash@{0}