In a 1953 speech, president dwight eisenhower listed some things that cost about as much as “one modern heavy-duty bomber”: a modern urban school, a couple of power plants or hospitals, or 50 miles of highway. what points was he trying to make?

What is a "one modern heavy-duty bomber"? It's a weapon, constructed to destroy lives (in order to protect other lives and goods).

What are the other things?

a modern urban school,
a couple of power plants or hospitals,
or 50 miles of highway.

all those things serve to improve people's lives and are not used in destructive ways. So what president Eisenhower was saying that instead of buying destructive weapons, we could invest in development - peace is better than a war.