Let's say I am applying for a position as a software developer and the company to which I'm applying says they offer training. I'd like to know what exactly training is? Is it akin to an unpaid internship? Do you have to go to classes, learn from home, or does the company choose an employee to help get you up-to-date with everything?
It means that the company accepts that you might not have all the technical experience required for the role, and is willing to train you on the job.
Typically, it's not akin to an unpaid internship - you will be paid your standard salary while training. ie. Attending training is your job description for the first few weeks.
As far as what training entails - it may be attending an official course, or it may be simply working under the mentorship of an experienced colleague.
These questions you can ask the employer directly, either at the interview, or before applying, ring them and ask what the training entails.