1. What does it mean?
가즈아 stretches and stylizes 가자. It is a rallying cry for a team, a hoped-for result, or something the speaker is excited to start. Extra vowel letters may make the written cheer feel even longer.
Also written or said as gajeua
2. The nuance
It also appears in investment chatter, where it expresses hope rather than reliable information about prices. Outside that context, it can simply be a playful burst of excitement.
3. Examples
“마지막 곡 시작하니까 친구가 가즈아를 외쳤어.”
When the final song began, my friend yelled, 'Let's gooo!'
“다 같이 결승 응원하러 가즈아!”
Let's all go cheer at the final!
Sources
References support the meaning and usage. Example sentences are written for NoCapWiki.