The first thing in Romans 11 talks about is how God did not reject his own people. It says: It is the same today, for a few of the people of Israel have remained faithful because of God's grace- his undeserving kindness in choosing them. (6) And since it is through God's kindness, then it is not by their good works. For in that case, God's grace would not be what it really is- free and undeserving. (Romans 11:5-6 NLT). These verses are talking about how God loves us and he will forgive us. It also talks about how we don't deserve his grace. It also talks about the people's good works are not what saves them but it is actually God's grace. Have you ever felt that you did not deserve something?
Now if the Gentiles were enriched because the people of Israel turned down God's offer of salvation, think how much greater a blessing the world will share when they finally accept it. (Romans 11:12 NLT). I like this verse because it talks about how if everyone accepts God then everyone will be happy and we will all be with him in heaven we also probably get way more done. Then it starts talking about how God is both kind and severe. He is kind if you trust in him but if you stop trusting him he will be angry with you.
Then it talks about how God will save everyone as long as the Gentiles come to him. It talks about how great God is because of his mercy for us.