With accent marks:
Де́лу вре́мя, поте́хе час.
Time for business, an hour for fun.
This is the expression of the Russian Tsar Alexei Mikhailovich (1629 - 1676) written by him in a book dedicated to falconry.
Meaning: most of the time shoud be dedicated to business (work) and duties, and less time - to entertainment.
It is usually said as a reminder to a person who, having fun, forgets about his duties.
Other Russian proverbs
Strike the iron while it's hot.
The quieter you go, the further you'll get.
Measure seven times, cut one.
Do not dig a hole for another one, you will fall into it yourself.
Patience and labor will grind everything.
If I knew where I would fall, I would lay some straw there.
Get your sleigh ready in summer and your (horse-drawn) cart in winter.
Make a fool pray to God - he will break his forehead.