Hi. Im Atiqah. I will visit China in January next year. So How to take a subway from terminal 2 Airport to Beijing Lucky Family Hostel?

You can take the airport express line to reach Dongzhimen Station and then take a taxi to reach your hotel directly.
The subway system use both Chinese and English, so there is no need about the direction and no need to use a software.

Yes, the street names, and the subway has english names, but it will be really useful if you have a dictionary.

Try Pleco. Its available in applestore and googleplay for you to download onto your phone and does not require internet access to work.

Another I would suggest is nciku (but that requires internet access)