In this porn video tag, "tranny" refers to a transgender individual, typically someone assigned male at birth but who identifies and expresses a female gender identity. The term has evolved over the years and can be considered outdated or offensive by some. However, it is often used in the context of adult entertainment.
The phrase "gets sucked" indicates that there is an act of oral sex being performed on this transgender individual. In this case, a male partner is performing oral stimulation on the transgender person's genitals. This type of scene can be found in the transgender porn genre and often showcases a focus on pleasure and exploration of gender and sexuality.