Your baby's growing tower of babble indicates that she's moving ever closer to talking, though her ability to form words and sentences that sound like much of anything comprehensible is still many months away. You may hear the same syllable repeated over and over with variations in pitch and tone. Or your baby may make more complicated sounds, such as two or even three different syllables strung together. She is, in fact, experimenting with the sounds her voice can make by placing her tongue or lips in different positions — like a musician testing out a new instrument.
Even though your baby doesn't intend any "meaning" behind these pre-words, your attentiveness to them helps her learn their power and eventual purpose. Listen attentively, as if you understand her completely. Babble or talk back. This is also a great time to introduce your baby to animal sounds (like "baaa" or "quack quack"), whose novelty will be very entertaining.