このはしごをしっかり押さえてくれ。

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

ladder; stairs; going to several places in succession (e.g. barhopping)

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.

tightly (holding on); firmly; securely; strongly (built); solidly; sturdily; steadily; properly; well; sufficiently; hard (working, etc.); fully; completely; reliably; dependably; levelheadedly; shrewdly; wisely; cleverly

to pin something down; to hold something down; to hold something back; to stop; to restrain; to curb; to seize; to grasp; to arrest; to gain control of something; to govern; to keep down (e.g. information); to suppress; to catch happening; to determine (important points); to find (proof); to understand