To unzip a file using your Android phone, you will have to install EASY UNRAR LITE from Google play store.
How to Use
*After installing the app, Click on Easy Unrar Lite to open the app
*Scroll and check for the folder that has the file you want to unzip.
*Tick the box in front of the file you want to unzip.
*Click EXTRACT ALL HERE (you will see it at the top of the app)
*You will see the extraction in progress as shown below, just allow it to complete.
*When it reaches 100% it will show Finish as in the pic below.
* Click on BACK.
Go out of Easy Unrar Lite. Go to the folder you initially kept the file in.
You can now do whatever you want to do with it. (Your zipped file can be in any folder on your memory card, and that is where the app will also keep the unzipped file for you)