With accent marks:
Гото́вь са́ни ле́том, а теле́гу зимо́й.
Get your sleigh ready in summer and your (horse-drawn) cart in winter.
This proverb reminds us to plan what we want to do and what we will need to do in advance so that any difficulties and unforeseen situations do not catch us by surprise.
There is almost the same proverb in English: "Repair your cart in December, in July your sledge remember".
Other Russian proverbs
You see your friends in the times of trouble.
If I knew where I would fall, I would lay some straw there.
Where it is thin, it breaks.
Being a guest is good, but being at home is better.
In a healthy body, healthy mind.
Hurry to much and you will make people laugh.
Don't bring your set of rules in a foreign monastery
The quieter you go, the further you'll get.