I tried to re-download my Snapchat app and it won't let me

So I "offloaded" my Snapchat app honestly I don't even know what that means or is but I tried to re-download my Snapchat app and it won't let me! It says it's loading but then it stops this happened with another app also but I really didn't mind because I didn't need it but I actually need my Snapchat app. Please someone help??!

[Re-Titled by Moderator]