The strings on a ukulele are tuned (from low to high) to G, C, E and A. This is the same as the top four strings on the guitar at the 5th fret, shown in the diagram above.
The big benefit here is that anything you can play on the top four strings of your guitar can be transferred onto a uke. However, standard tuning on a uke is a bit different to a guitar because the fourth string is raised by an octave, which means that the lowest string isn’t actually the lowest note.
This is unconventional for guitarists but it shouldn’t present any problems when it comes to chords - just keep it in mind when you’re playing melodic lines. Plus, because of the ukulele’s short neck, you don’t have to worry about winding the strings to breaking point to get the correct pitch.