"Thing" as a feminine singular noun and "what" as an interrogative are English equivalents of the Italian word cosa. The choice becomes clear with context since use in the first-mentioned case may be preceded by the feminine singular definite article la ("the") or indefinite una ("a," "an"). Regardless of meaning or use, the pronunciation will be "KO-sa" in Italian.
"What" in English is Che?, Che cosa? or Cosa? in Italian.
"What was that?" in English is Che cosa era? in Italian.
Che cosa
"What is...?" in English is Cos'è...? in Italian.
Checca in Italian means "gay (homosexual)" in English.
"What are you staring at?" in English is Cosa stai guardando? in Italian.
"How about you?" in English is Cosa mi dici di te? in Italian.
"I will see what I can do" in English is Vedrò cosa posso fare in Italian.
Cosa sta facendo (lei)?
L'amore è un'altra cosa! in Italian means "Love is another thing!" in English.
Non so che cosa fare in Italian means "I don't know what to do" in English.
.cosa fai stasera