This is the 12317th most frequent Portuguese word.
seda
Silk.
Here, 'seda' refers to the silk material the tie is made of.
Esta gravata é de seda.
This tie is made of silk.
In this context, 'seda' means the silk thread that spiders produce.
As aranhas produzem seda para tecer suas teias.
Spiders produce silk to weave their webs.
Here, 'seda' is used metaphorically to describe the smooth and soft quality of his voice.