So, cisgender is a person whose gender identity matches the gender at birth. Simply put, you were born with a female set of organs and XX chromosomes, you feel like a woman, which means you are cisgender.
This term was introduced in order not to divide people into transgenders and “normal”: you must admit, this is not very pleasant.
Of course, learning to define yourself as cisgender in one day is not easy, but until quite recently we hardly used, for example, the word “heterosexual”. And new times dictate the emergence of new terms in the language.
Cisgender is just a gender. That is, a person, being cisgender, can be hetero-, homo-, bisexual. The same, by the way, applies to transsexuals, whose intimate life can develop with representatives of either sex.
At the moment, the word “cisgender” is a neologism for the Russian language and is used infrequently. But over time, it will certainly become more widespread.