What does it mean to have latent TB infection (ltbi)?

Dormant infection. Latent TB means you have been exposed to TB somehow, and its dormant (sleeping) in your body, suppressed by your immune system, but not fully removed.
Dormant. It means that the person carries the bacteria that cause TB in a dormant stage, typically no symptoms are noted, and it is a non contagious state. In contrast, when TB is active, there is a raging fight with TB having the upper hand, several symptoms are noted, the person is usually coughing and transmitting the disease.
Protect yourself. Take med to protect yourself and see lung expert probably inh for nine months.