Hello
The condition should only be met if nameABC says it.
on *:TEXT:*hello*:#channe123:{
if ($nick == nameABC) msg $chan hey $nick <3
}
on *:TEXT:& gives a high 5 to &:#channe123:{
if ($1 ison $chan) && ($7 ison $chan) msg $chan $7 got a high 5 from $1
}
on *:TEXT:& gives & high 5s to &:#channe123:{
if ($1 ison $chan) && ($3 isnum) && ($7 ison $chan) msg $chan $7 got $3 highs 5 from $1
}
The last two codes could indeed be merged using regex, (or maybe still even using wildcard) but if you don't know how to make this without regex it's probably not a good idea to try to start using regex right now, at least I don't recommend it.
Check
https://en.wikichip.org/wiki/mirc/conditional_statements &
https://en.wikichip.org/wiki/mirc/operators to learn more about if statement and the different operator mIRC supports.