At least in theory the extra cash raised by selling the new stock makes the company more valuable, so your shares remain worth the same before and after. Actual practice is a lot more nuanced - the company might not be able to sell the new stock at a high enough price, or they might spend the new money immediately on hookers'n'blow^W^W^W unsound investments.
The other answer to this is correct, but a little more detail in case you're interested:
^W is a control code. This specific one represents the keys ctrl+w, a keyboard command in Vi and Bash among other things. It deletes the previous word. You often see something similar with ^H as well, which is a single-character backspace. https://en.wikipedia.org/wiki/Backspace#^W_and_^U has some more information about these.
Some people use them more to make visual jokes in written text, more or less the same way you'd use strikethrough formatting in text.
And in my experience ties in nicely with the fact that when a dumb terminal glitched or lost sync with the server, control codes would start to litter the screen instead of being interpretted. You'd see things like:
…thsi typo^Ŵ^H^H…
start to appear, sometimes followed by several random letters hit in frustration, before the final hard-reset of the terminal and resignation to the fact some unsaved work has been lost.
Depending on the company bylaws you typically need at least a simple majority of the votes / stocks to issue new stocks. The company can also have a rule that says that existing share owners must have the right to purchase before everyone else, to "defend" their stake.
In general companies typically raise money because they think the cash infusion will benefit the existing shareholders in the long run, either by not going into ≈bankruptcy or having the cash to do investments / move into new markets etc.
Shares do not imply ownership but participation. That participation can take different shapes, depending on the type of shares and the bylaws of the company: some will be entitled to dividends, some will be entitled to voting on decisions, some will entitle to a form of ownership, etc etc.
It does entitle you to ownership, you as an investor in the company presumably approved the issuance of new shares on the belief that the additional capital would make your investment worth more in the future.