Can't use non-numeric string as operand of "&&" in rule

Here is your code formatted:

when HTTP_REQUEST {
    set uri [string tolower [HTTP::uri] ]
    /_hst name and ?_hst=1 parameter triggers client cert renegotiation
    if { !($renegtried) and ([SSL::cert count] == 0) and (([HTTP::uri] equals "/extern/test.jsp") or ([HTTP::uri] equal "/SO/services/dat") or ([HTTP::uri] equal "/test/services/Tasacion") or [(HTTP::uri] equal "/Ex/services/pay")) } {
        log local0. "[IP::client_addr]:[TCP::client_port]: A log entry"
        HTTP::collect
        SSL::cert mode request
        SSL::renegotiate
    }
}

You have some oddly placed characters (for example, "[(" and sometimes you put "equal" rather than "equals"). In any case, a switch for equality will be easier to read:

when HTTP_REQUEST {
    switch [HTTP::uri] {
        "/extern/test.jsp" -
        "/SO/services/dat" -
        "/Ex/services/pay" {
            if { !$renegtried && [SSL::cert count] == 0 } {
                log local0. "[IP::client_addr]:[TCP::client_port]: A log entry"
                HTTP::collect
                SSL::cert mode request
                SSL::renegotiate
            }
        }
        
    }
}

Note that I removed the string tolower. Ordinarily, URI paths are case-sensitive (assuming your server and filesystem are) so the conversion is of no real value. Indeed, you perform the conversion, assign the value to $uri then never reference that variable. If you really do care, you can simply substitute that back in.