I'd like know how the underlined it and that is used.

Question

You may think you found the ultimate answer to career choices or maybe you’re as confused as ever. Regardless of the side you’re on, the best advice for navigating these important life choices is this: Take a flexible attitude toward career choices. As smart and dedicated as you may be, you just can’t predict the future. Some of the most successful professionals in any imaginable field could never ever have predicted what they actually do today. Why? Because when they were in high school, those jobs didn’t even exist. (It was not too long ago that there were no such things as the Internet, cell phones, or any of the other new tools that are so critical to so many jobs today.) Being open-minded increases future opportunities.

Would you tell me whether the underlined 'it' is used as placeholder or 'it is(was)~ that' emphasis ?

Answer 1

"It" is a relative pronoun referring to "the time," in this case. The word "that" could have easily been replaced with the word "when," which, in that case, as the word "when," it would have fulfilled the role of a subordinating conjunction. Therefore, since "that" is acting as a synonym for "when," then the word "that" is also a subordinating conjunction in this sentence.