Strategic block investing is when a big person (like a company or rich person) buys a really big chunk (block) of a company's stock all at once. This kind of buying happens when a big person thinks that the company is going to do really well in the future.
When a big person buys a lot of a company's stock, it can make the price of the stock go up. This is because when there's more demand (people who want to buy) for a stock than there is supply (stocks available to buy), the price goes up.
If the big person who bought the block of stock is right and the company does well, then the value of their block of stock will go up too. This can make the big person a lot of money if they decide to sell it later. However, if the company doesn't do well, the value of the stock might go down and the big person could lose money.
Overall, strategic block investing is a way for big people to try and make a lot of money by buying a lot of stock at once in companies they think will do well in the future.