Ukrainian visas are issued within 3 types:

• transit (B type) visas. B type visas are issued in cases where a foreigner/stateless person intends to transit through Ukraine and each transit period does not exceed 5 days. B type visas are issued as single / double / multiple entry visas valid for a maximum of 1 year or another period depending on supporting documents. 
• short-term (C type) visas. C type visas are issued in cases where a foreigner/stateless person intends to stay in Ukraine for up to 90 days within every 180 days. C type visas are issued as single / double / multiple entry visas valid for 6 months or another period depending on supporting documents but cannot be issued for more than a 5 year-term.
• long-term (D type) visas. D type visas are issued in cases where a foreigner/stateless person intends to apply for a temporary residence permit to stay in Ukraine for more than 90 days. D type visas are issued as multiple entry visas valid for 90 days.

Please find more information at https://mfa.gov.ua/en/consular-affairs/entry-and-stay-foreigners-ukraine/visa-information 

Check whether you need a visa to enter Ukraine here