Corrected sentence: Reindeer hooves are soft in the summer and hard in the winter, so they can dig in the snow.
Why this is better (easy steps):
- Use "the" before "summer" and "winter" to sound natural: "in the summer" and "in the winter."
- Avoid repeating "the reindeer" twice. Use the pronoun "they" instead: it means the same and sounds smoother.
- We put a comma before "so" because it shows the result (why the hooves change): the hooves are hard in winter, and because of that, they can dig in the snow.
- Words like "soft" and "hard" are adjectives that describe the hooves.
Other correct version (shorter): Reindeer hooves are soft in summer and hard in winter so they can dig in the snow.