Your baby can now repeat sounds in one breath

The repetition of a syllable, such as "ba ba ba ba," is known as 'reduplicated babble'. Babbling is a way for your baby to practise sounds and oral motor skills that are needed for speech.

Your baby is copying you

Your baby may now generate multiple noises in a single breath and will try to imitate adult sounds. This experimentation with sounds represents speech and they are developing the rhythm of words used in language.

Your baby may now also start to move when they babble, imitating natural gestures used in conversations.^[1]

References:

[1] M.M. Vihman (2014) Phonological Development: The First Two Years. Blackwell Publishers.