このガイドブックは君が旅行の計画を立てるの役立つだろう。

this (something or someone close to the speaker (including the speaker), or ideas expressed by the speaker)

guidebook

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

you; buddy; pal; monarch; ruler; sovereign; (one's) master

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

travel; trip

indicates possessive; nominalizes verbs and adjectives; substitutes for "ga" in subordinate phrases; (at sentence-end, falling tone) indicates a confident conclusion; (at sentence-end) indicates emotional emphasis; (at sentence-end, rising tone) indicates question

plan; project; schedule; scheme; program; programme

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

to stand up; to put up; to set up; to erect; to raise; to thrust into; to bury into; to dig into; to make (a noise); to start (a rumour); to raise (a cloud of dust, etc.); to cause; to make; to establish; to set up; to develop; to formulate; to put up (a political candidate); to make (one's leader); to treat with respect; to give (someone) their due; to make (someone) look good; to avoid embarrassing (someone); to sharpen; to make clear; to shut; to close; to make tea (macha); to perform the tea ceremony; to divide by; to do ... vigorously

to be useful; to be helpful; to serve the purpose

be; is; indicates past or completed action; indicates light imperative