Business Mileage Credit Card VISA Mileage Plus Good? (Chase Credit Card)?

VISA Mileage Plus good? (Chase credit card)? - business mileage credit card

As stated in the document to the letter --
"Earn 20.500 bonus miles after first purchase"
"Earn 1 miles for every $ 1 in qualifying purchases"
"No annual fee for the year 1 ($ 60 after 1 years).
* And, of course, see the attached letter for more information ....

Is the use or possession of a person, this card with United Airlines?
Is it worth it? What kind of "Eligible Purchases" are talking about? I just started a new job a month ago and need to build a business credit card from my credit card, and I am a mileage AU member.
Thank you for answering!