built an altar to Yahweh
"built an altar dedicated to Yahweh" or "built an altar for worshiping Yahweh." He may have built it with stones.
clean animals ... clean birds
Here "clean" means that God allowed these animals to be used in sacrifice. Some animals were not used for sacrifices and were called "unclean."
offered burnt offerings
Noah killed the animals and then completely burned them up as an offering to God. AT: "burned the animals as offerings to Yahweh"
This refers to the good smell of the roasted meat.
said in his heart
Here the word "heart" refers to God's thoughts and emotions.
curse the ground
"do very serious harm to the earth"
because of mankind
This can be made more explicit: "because mankind is sinful." (See: rc://en/ta/man/translate/figs-explicit)
the intentions of their hearts is evil from childhood
"from their earliest years they tend to do evil things" or "when they are young, they want to do evil things"
the intentions of their hearts
Here the word "hearts" refers to people's thoughts, emotions, desires, and will. AT: "their tendency" or "their habit"
This refers to an older child. AT: "from their youth"
While the earth remains
"While the earth lasts" or "As long as the earth exists"
"the season for planting"
cold and heat, summer and winter
These expressions both refer to two major weather conditions in the year. Translators may use local expressions. (See: rc://en/ta/man/translate/figs-merism)
the hot, dry time of the year
the cool, wet or snowy time of the year
will not cease
"will not cease to exist" or "will not cease to occur." This can be expressed in a positive manner. AT: "will continue" (See: rc://en/ta/man/translate/figs-doublenegatives)