Getting Adsense account approved used to be pretty easy back in the day when it was first started. All you needed was a website with some content and you'd get instantly approved.
Now you need a quality website that has great navigation, quality content, and an About and Terms of service page.
Even then it can still be hard to get an adsense account approved and can take many tries.
If you get rejected for an adsense account don't apply again right away. Give it time and in that time continue on improving your website and adding more great content and work on the design.
Wait about 6 months before applying again for an adsense account after getting rejected.
There's also a 2 part approval process for Adsense now. Once you get to the first step you'll be presented with an Adsense account where you'll then need to place the Adsense code on your website.
Then it can take up to a month before the second part of your website is approved. If you see adsense ads on your website then it means your account has been approved.