Keyword Analysis & Research: what is the plus sign with a line under it

Keyword Analysis

Keyword	CPC	PCC	Volume	Score	Length of keyword
what is the plus sign with a line under it	1.96	1	3427	86	42
what	0.42	0.2	1269	63	4
is	0.81	0.7	5844	16	2
the	1.41	0.5	8011	58	3
plus	0.97	0.8	9812	53	4
sign	0.06	0.2	2395	71	4
with	0.4	0.8	2024	89	4
a	1.27	0.5	3621	39	1
line	2	0.1	3478	83	4
under	1.02	0.1	1673	61	5
it	0.1	0.3	3995	55	2

Keyword	CPC	PCC	Volume	Score
what is the plus sign with a line under it	1.25	1	9746	45