。
I plan to take care of my parents when they get old.
Literal
Parents [subject-が] age take [conditional-たら] care [object-を] see intention is.
~つもりです (I plan to / I intend to) expresses a firm intention. 年をとったら (when they get old) uses the たら conditional for a future eventuality. 面倒を見る (literally 'to see the trouble') is the standard idiom for taking care of someone — used widely for children, elderly parents, the sick, or pets.