Questions & Answers about Мама сошьёт мне тёплый халат.
Сошьёт is the perfective future form of сшить, which means to sew/make something and finish it.
So this form focuses on the completed result: the robe will get made.
- шить = to sew, to be sewing, to sew in general
- сшить = to sew something together, to make by sewing, to finish sewing
Compare:
- Мама шьёт халат. = Mom is sewing a robe / Mom sews robes.
- Мама будет шить халат. = Mom will be sewing a robe.
This emphasizes the process. - Мама сошьёт халат. = Mom will sew a robe (and it will be finished).
This emphasizes the completed outcome.
In this sentence, Russian chooses the perfective form because the idea is that the robe will be made for someone.
Сошьёт is:
- 3rd person singular
- future tense
- perfective aspect
- from the verb сшить
So it matches Мама:
- Мама сошьёт = Mom will sew
The ending -ёт is the normal 3rd person singular ending for this verb form.