What is the meaning of "Kol ha'Yom Chonen u'Malveh"?
Rashi: The entire day, a Tzadik is gracious to Aniyim and lends to them.
Radak: All days [he is gracious and lends]. The same applies to "Osecha Kivisi Kol ha'Yom" (25:5). Even when he has [financial] pressure, he is gracious and lends according to his ability.
What is the meaning of "v'Zaro li'Vrachah"?
Rashi: What he seeds for Tzedakah, in the end it will be for a Brachah.
Radak #1: His seed learn from his ways; they are a Brachah to the world - they give from theirs to those who need. This is like "v'Heye Brachah" (Bereishis 12:2) - give to others from your Brachah and good.
Radak #2: People will bless his seed when they see them, and say 'these are the seed of a Tzadik; Hashem should bless them in their father's merit.'
Malbim: Even if a Tzadik is gracious and lends until he becomes poor, his merit will cause a Brachah - his sons will succeed.