Translation:She is going to change the date of the party.
This pronunciation of the "va a" is extremely poor. These 2 separate words become 1 when she pronounces them - indistinguishable. I have amigos Latinos and when I ask them to pronounce it I can clearly hear the separation. The original female speaker's I used to listen always pronunced clearly and better paced the phrases. I don't hold to others arguments that "in real life every person will speak different speeds so get uses to it". I understand that - but we are here to learn. Once I have a good grasp of the language, then I can engage in the day to day immersive experience of dealing with different speakers. Simple andragogical fundamentals.
The voices here aren't specifically designed for learners, but they are parts of a commercial TTS.
Spoken Spanish does not use glottal stops or different vowel lengths, so neighbouring vowels will run into each other when speaking. A similar thing happens in English if you pronounce "I can see a little": the "a" will vanish into the "see" if you don't speak especially carefully.