Romans 1:16 says “For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek.“
The greek word for gospel is euaggelion which is translated “good message” or more commonly as “good news”.
What is that good news?
The apostle Paul defines that good news in 1 Corinthians 15:3-4
 Moreover, brethren, I declare unto you the gospel which I preached unto you, which also ye have received, and wherein ye stand;
 By which also ye are saved, if ye keep in memory what I preached unto you, unless ye have believed in vain.
 For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures;
 And that he was buried, and that he rose again the third day according to the scriptures
You put the scriptures in Romans 1 and 1 Corinthians 15 together, and you can see that the death, burial, and resurrection of Jesus is God’s power for salvation to everyone that believes.
That word power is the Greek word dynamis which is also translated “ability”. The power of God can do harm. The power of God can destroy as well as create. The power of God can kill you. But the gospel is the power of God unto salvation. The gospel will not harm you. If you believe the death, burial, and resurrection of Jesus, that power can only benefit you.
What is salvation? The Greek word for salvation in Romans 1:16 is sōtēría, which is also translated as deliverance, health, preservation, safety, etc. It is anything you have need of.