This is the 397th most frequent Polish word.
krwi
The Polish word "krwi" means "of blood" or "blood's" (genitive singular form of "krew").
"Krwi" is used here in the context of describing blood type, signifying possession or relation to blood.
Mam grupę krwi o typie A.
I have a blood type A.
"Krwi" here is used as a direct object in the genitive form, indicating what is being referred to in the context of sight.
Nie mogę patrzeć na widok krwi.
I cannot stand the sight of blood.
"Krwi" is used to denote the material needed, again in the genitive case, reflecting necessity and quantity.