"Keep in mind" is a common phrase that means "remember".
"Take in mind" isn't a phrase anyone uses, but WOULD mean "think about" or "consider".
At least he was inventive.
He's just saying that two coins with different quantities, but the same market capitalization, would have a different price per coin. When predicting a price it's best to predict the market cap and then divide by the number of coins to get the actual price prediction.
Example:
If you think STRAT should have a market cap of $100,000,000, and there are nearly 100,000,000 coins, that's $1 per coin, or about 0.00156250 BTC.
If another coin should have a market cap of $100,000,000, but only has 50,000,000 coins, that's $2 per coin, or about 0.00312500 BTC.