This is the 14935th most frequent Russian word.
поджигать
To set on fire; to ignite deliberately.
In this sentence, 'поджигать' is used in its neutral sense, meaning 'to light something on fire'.
Я люблю поджигать свечи вечером.
I like to light candles in the evening.
Here 'поджигать', in past tense as 'поджёг', is used to describe starting a fire for a practical purpose.
Он поджёг костёр, чтобы мы согрелись.
He lit the campfire so we could warm ourselves.
In this context, 'поджигать' signifies a deliberate act of arson, which is illegal and carries negative connotations.