Levi Ackerman, aka humanity’s strongest soldier, is one of the major characters of AOT.
Leviwas born in an underground slum of Paradis; his mother, Kuchel Ackerman, was a prostitute, and she had to raise her son single-handedly as she was impregnated by one of her clients.
Kuchel battled to provide financially as a single parent, but she loved her son and did everything possible to take care of him.
Regardless of her efforts, they were poverty-stricken, and filth was inevitable as they lived beneath a city; plus, Levi’s mother suffered from an unknown disease; hence she died at an early age.
As a result of his early life, Levi is portrayed as a clean freak.
Kenny Ackerman, Kuchel’s elder brother, once went underground to check on his sister, but he found her sister dead.
Kenny found Levi in a skeletal state, almost on the verge of dying; hence he decided to take care of him in a rare showing of sympathy.
Kenny was a cold-blooded killer who earned the nickname “Kenny the Reaper” from his preferred method of murder.
The principle of survival solely governs Kenny’s parenting style; he prioritizes training Levi with combat skills necessary for living among bandits, frauds, and murderers.
Once Kenny is happy with Levi‘s ability to survive, he leaves him.
Levi then becomes a notorious thug but eventually comes under the discipline of commander Erwin Smith; Erwin convinced Levi to join the Survey Corps as a soldier to fight the titans and protect humanity.
Later on, Levi becomes one of Erwin’s most trusted men. When Levi joined the Survey Corps in 844, he was around 24 years of age, and at the time of the last arc War for Paradis Arc, Levi Ackerman’s age was approximately 33 years.
Hence to answer your question, Levi Ackerman’s current age is 33 years in Attack On Titan.