Repeating a mantra is a great way to keep focused while meditating. Especially when you are just starting out, it can be very difficult to keep your mind from running away from you. Mantras help keep your mind still and focused on one single thing, not giving your attention a chance to wander.
In my opinion, repeating a mantra in another language is even more effective, because you are not associating the words with anything familiar. Nothing in the words will trigger associated thoughts.
One of my favorite mantras to repeat is the Ganesha Mantra. Ganesha is the Hindu elephant-headed deity in charge of removing obstacles.
You do not need to be affiliated with any religion for this mantra to work for you. It can help to calm you and focus your meditation regardless of your religious beliefs, or lack thereof.
The recommended number of mantra repetitions is 108 times. It's easiest to keep track of the number when using a necklace with 108 beads for this purpose (mala beads). If you are repeating the mantra for the purpose of removing obstacles from your life, it's widely recommended to repeat the mantra for at least 40 consecutive days.
The Ganesha Mantra is as follows:
Om gam ganapataye namaha
You can listen to the mantra repeated here.
Sometimes instead of simply repeating the mantra myself, I like to listen to my favorite musical version of the Ganesha Sharanam mantras, sung by Jai Uttal. It never fails to lift my spirits!