I once asked my Jyotish guru, K.N. Rao, if it's necessary to understand the meaning of mantras in order to get their benefit. His response was, "Mantras are medicine. I don't need to know the ingredients of my medicines for them to work." When I thought about this it made sense. If it's true that all languages emit a vibration, and Sanskrit is a spiritual language, then we can benefit by the vibration of mantras without knowing their meaning. It's like when you hear beautiful music sung in another language, like at an Italian opera, and you feel uplifted regardless of knowing the language. Sanskrit mantras are the same way, only more powerfully, because the language was developed for purpose of spiritual transformation.
Read an article about the use of the Vishnu Sahasranam as a remedial measure for planetary afflictions by clicking here.