Let’s learn Japanese with manga. What you are going to learn on this page is:
When you read manga, you read from right to left.
It is used before you start to say something. Similar words are それじゃあ and それでは. それじゃ and それじゃあ are informal. それでは is formal.
It is used when you start to drink. かんぱい is 乾杯 in Kanji. 乾 means ‘dry’ and 杯 means ‘cup’ or ‘glass’. So 乾杯 literally means ‘to make your cup dry (by drinking all)’.