From Google:

"A homograph attack, also known as an internationalized domain name (IDN) homoglyph attack, is a type of cyber attack that uses similar characters to trick users into communicating with a remote system that is not what it appears to be: 

Homograph attacks use characters that look similar, but represent different sounds or phonemes in different writing systems. For example, the Latin letter "a" and the Cyrillic letter "а" look nearly identical. Hackers can use these characters to create domain names or URLs that look legitimate but are actually malicious."