For tax years 2018 through 2025, you can’t claim a personal exemption ?

Hello, I am filing ITIN along with return for my spouse for the first time. We don't have ITIN before. This year would be first time we doing. I don't understand what IRS mean by,

"For tax years 2018 through 2025, you can’t claim a personal exemption deduction for yourself, your spouse, or your dependents." 

In other words, there is no specific benefit for spouses form 2018-2025 so you shouldn't apply for or renew an ITIN.  Finally, looking to the 1040 Instructions:

What does that mean in simple words. I was filing as single and now it would be married jointly. What changes will i have?