You can use 'unnumbered
or hidden-number
style as documented in the para
documentation.
These two styles have similar, but slightly different uses:
'unnumbered
is when there is no number associated with this section. Use this when you do not want to reference a section and want the next section to have the next incremental number.
'hidden-number
is when the section does have a number, but it is not shown. This causes the next section to jump up a number, but you can still reference it.
The following code will cause the document to look like you want:
#lang scribble/lncs
@section[#:style 'unnumbered]{First Section}
@section[#:style 'unnumbered]{Second Section}
@subsection[#:style 'unnumbered]{A subsection}
@section[#:style 'unnumbered]{Third Section}
The document will look something like:
First Section
Second Section
A subsection
Third Section