The reason why 95% of people start learning the guitar, is because they want to be able to play songs. This is totally natural, since the point of playing an instrument is to make music. Only few people have set goals with the guitar, such as professional musicians or composers, but for most beginner guitarists, being able to play famous guitar songs will suffice.
Hence the big question, how long will it take before beginners can actually play the songs they like? The answer depends on several things, but mostly, how much practice time you can put into learning the guitar. The more you practice, the better you'll get, and the more you'll actually want to practice, since you'll have loads of fun playing new songs.
How much do you practice?
Unfortunately, learning the guitar is not exactly the easiest hobby you'll undertake. The payoff is humongous, but many beginners decide to quit after a couple weeks when they start running into difficulties, before they have any real success.
The only way to learn to play the guitar is to practice regularly. If you practice once every two weeks, you can't honestly expect to get very far. But if you practice at least every other day, you'll be playing simple songs to your friends and family in no time at all.
What kind of songs do you want to play?
You can start playing beginner songs that require being able to strum a few simple chords very quickly, after about 2 weeks of practice, all you'll need to do is to learn to change between chords. If you are at a very beginner stage, have a go at these beginner guitar songs, they're loads of fun and you'll find video guitar lessons with animated tabs to all of them on TheGuitarLesson.com:
Of course, playing songs such as More Than Words by Extreme will require much more practice time, but by starting to play easier songs right at the beginning of your guitar journey, you'll remain motivated to keep on learning and practicing.
What style songs do you like?
If you are into punk, you'll be happy to know that by learning to play power chords, you'll already be able to play lots of punk songs. If you prefer classical music, you have a long way to go before you can truly play the classics, but there are cover versions of many masterpieces totally suited for beginners. If you want to play like Eric Clapton, well, the guitar has been his life for decades, but you can have a go at Layla after about a year of regular practice. Don't let this demotivate you though, being able to play more complicated songs is totally achievable, it just takes a bit more time and dedication, as with all things worthwhile in life actually.
Stick with it, practice regularly, and you'll soon see that choosing to learn the guitar was one of the best decisions you've ever made.