‘God enlarge (yaphth) Japheth and let him dwell in the tents of Shem, and let Canaan be his servant.'
The word ‘enlarge' is a play on Japheth's name. In 1 Chronicles 5:10 ‘dwell in the tents of' suggests being subjugated. However here it more probably refers to them receiving benefits from ‘Shem'. The ‘enlargement' suggests blessing but also looks forward to the increase of the nations in the next chapter, which is of course part of that blessing.
Note that Canaan is to be servant to both. His servitude is mentioned three times to stress its completeness. But it must not be overlooked that the curse is primarily on Canaan's descendants and not on Ham's. Ham's would themselves become great nations. These ideas have been widely distorted to defend an indefensible racism.
We note again how the divine names are used. In blessing Shem He is Yahweh. In blessing Japheth He is Elohim. The descendants of Shem are to be the people of the covenant.
Ham receives no blessing. All that is offered to him is the curse on Canaan. In this there is both mercy - the curse is limited - and judgment - he is excluded from the blessings. Noah could never forget what Ham had done to him.