They are still several light years away from the sun, so "near" only on astronomical scales. "Brown dwarf" is an object bigger than a usual planet, but not big

They are still several light years away from the sun, so "near" only on astronomical scales. "Brown dwarf" is an object bigger than a usual planet, but not big enough to spark and sustain nuclear fusion in the core. "cold" means "not hot enough to shine bright like a star".