This is the 4406th most frequent Swedish word.
trolig
Likely.
In this sentence 'trolig' is used as an adjective describing the suitability or likelihood of someone being chosen as a candidate.
Han är en trolig kandidat för jobbet.
He is a likely candidate for the job.
Here 'troliga' is an adjective modifying 'förklaringen' (the explanation), indicating that the explanation is plausible or probable.
Den troliga förklaringen är att hon missade bussen.
The likely explanation is that she missed the bus.
Here 'troligt' is used as an adverb describing the plausibility of the event of rain occurring.