Regarding the expressions "solicited" and "unsolicited". Firstly, try to get "the dictionary habit" and look up unfamiliar words by habit. "Solicited" material means the publication asked you to write it for them. That is, they solicited it from you. Unsolicited means you sent something to the publication without them either asking you for it, or pre-agreeing to look at it such as in a phone inquiry.
This is not just a vocabulary lesson. The difference between solicited and unsolicited work shapes how you get paid, how you are treated, and how much risk you carry, so it pays to understand it in your bones.
Solicited work is the comfortable kind. An editor has asked you for a piece, which means they have budget for it, space for it, and a reason to run it. You can usually talk about the fee and the deadline up front, and you can get to work knowing there is a buyer waiting at the other end. This is where you want to be, and every freelancer's aim is to turn editors into people who ask.
Unsolicited work is the gamble you start out playing. You write something on spec, send it in cold, and hope it lands on the right desk on the right day. Most of it is never used, and you carry the cost of the time you spent. That does not make it pointless. A strong unsolicited piece is how an unknown writer first gets noticed, and how you prove you can do the job before anyone has promised you a cent.
The smart path is to use the second to win the first. Pitch and submit on spec until an editor likes your work, then nudge the relationship towards "next time, ask me first". The day the requests start coming to you is the day the hard part is over.