Pfb is likely misspelled.
Pfb has no English definition.
As an abbreviation pfx is
prefix.
pfb
English
===(
en)===
(
en-abbr)
(knitting) purl into front and back of same stitch
* 2012 , Kristi Porter, Knitting In the Sun (page 137)
- Round 3: Pfb', work Row 3 of Chart A1 (A1, A1, A2, A2) twice, ' pfb .
pfx
English
Abbreviation
(Abbreviation)
(head)
prefix 