And now for a little space grace hath been showed. The "little space" must be understood relatively to the long enjoyment of Divine favour from Abraham to Zedekiah. It was a space of more than eighty years.
A remnant to escape. The Hebrew has simply p'leythah, "a remnant," the "remnant" being that which had escaped the two dangers of destruction and absorption, and had returned from Babylon to Palestine.
To give us a nail. "A nail" seems to mean here "a firm and sure abode," as our translators note in the margin.