Rashi on Genesis 33:12/רש"י על בראשית ל״ג:י״ב

1נסעה is an imperative like שִׁמְעָה and שִׁלָחָה which are equivalent to שְׁמַע "hearken!” and שְׁלֵח “send!” Similarly here, נִסְעָה is equivalent to נְסַע “travel on!”, where the נ is a root-letter of the word and not the prefix of the future in which case the word would mean “let us travel on”, similar to the following word ונלכה “and let us go”. The Targum also takes it in this sense, rendering it: “Travel on and let us go". Thus Esau said to Jacob, “Travel thou on from here and let us go etc.

2ואלכה לננדך means AND I WILL GO SIDE BY SIDE WITH THEE — I will do you this favour: that I will take a longer time on my journey by going slowly as is necessary for you. This is the meaning of לנגדך — alongside of you.