Dividend irrelevancy theory

Hello Tutor , below is the sentences I extract from the textbook which I don’t really understand. Its said it will no difference for the shareholder whether is financing from outside or cut in the dividend to a project .
1)If the additional outside finance is a loan, why the value of the share will reduce?
2)why the reduction in the value of the share = dividend paid?

Thank you.

“M&M’s theory states that provided a company is investing in positive
NPV projects, it will make no difference to the shareholder (and share
price) whether the projects are funded via a cut in dividends or by
obtaining additional funds from outside sources.
As a result of obtaining outside finance instead of using retained
earnings, there would be a reduction in the value of each share.
However, M&M argued that this reduction would equal the amount of the
dividend paid, thereby meaning shareholder wealth was unaffected by
the financing decision.”