Owner ask for 30k - 90 days lien. -HELP!

[Tu Phan]

hello honorable men!

I drop a business card "I buy houses cash" on random houses

And got a call and he left a message

He said he need 30k and ask if I can do a 90 days lien on his house,

I don't know what this mean, I'm only familiar with wholesale

So if you guys can help explain to me what he means so I can call him back with a solution.

Thank you so much !!