Verse Gn32-18 states three questions: And he commanded the foremost, saying, When Esau my brother meets you, and asks you, saying,
1. Whose are you? and
2. where are you going? and
3. whose are these before you?
Gn32-19 states a corresponding 3 responses Then you shall say,
1. They are your servant Jacob’s;
2. it is a present sent to my lord Esau; and, behold, also
3. he is behind us.

Thus Rashi here teaches the grammatical rules governing answering questions: A sequence of answers following a sequence of questions should be parallel: That is the first answer responds to the first question, the second answer responds to the second question, etc. This parallel rule is depicted above in the numbered lists.

Sermonic points: We have presented this Rashi as grammatical. But most people see this Rashi as indicating etiquette: It is proper etiquette to answer questions sequentially, rather than in a random order.