I'd like to organize a trip to Bucharest for 4 to 5 days but I only have the first week of July available. Is it a good time to visit or it's better to go in winter?
July is a good time to visit even if the weather can be very warm (over 30 C) , I assume that's what you were reffering to.
Anyway, 1-2 days are enough for Bucharest. Spend the rest of the time in Brasov or Sibiu and visit the mountains, castles, fortresses, old villages etc. around them - the weather will be cooler there.
I assume I can go there by train or by bus, right?
Also, I don't know the language will it be a problem?
Language isn't a problem, most tourists get by with English. When you need informations, directions etc try asking mainly young people.
I think July is a great time. If you go to Bran or Brasov it will be slightly cooler in those regions. With the trains, you can book online as well. Note that you only get a seat number in first class but other than that there really isn't a difference in the level of accommodation. If you are OK to get there a little early and claim a seat, don't go for the extra $$. I just put together an article of 10 things to do in Bucharest in Spring/Summer that may be helpful: https:/…. Enjoy your trip!