This is the 313th most frequent Italian word.
farlo
"Farlo" means "to do it" or "to make it" in English.
In this sentence, 'farlo' carries the infinitive form of the verb 'fare' with 'lo' as its direct object, signifying 'to do it' or 'to make it'.
Non so come farlo.
I don't know how to do it.
The phrase 'di farlo' here indicates intent to perform the action (to do it), following 'cerco' (I try).
Ogni volta che cerco di farlo, qualcosa va storto.
Every time I try to do it, something goes wrong.
Here, 'farlo' combines the verb 'fare' (to do/make) with 'lo' (it), functioning as an object pronoun to indicate the action to be performed.