Without further context, it is difficult to determine which wall Ronald Reagan may be referring to. It could be the Berlin Wall, as Reagan famously called on Soviet leader Mikhail Gorbachev to "tear down this wall" in a 1987 speech. However, it could also refer to other walls or barriers present during Reagan's presidency.
If you're referring to U.S. currency, then no, Reagan is not on any bill.
In 1987 Reagan demanded the fall of the Berlin Wall, while speaking nearby at the Brandenburg Gate in West Germany.
As president Ronald Reagan was famous for several things. Perhaps he is most famous for saying (while at the Berlin Wall), 'Mr. Gorbachev, tear down this wall.'
President Reagan
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President Ronald Reagan
Ronald Reagan.
President Ronald Reagan
Mikhail Gorbachev
The Berlin Wall
Ronald Reagan gave a speech to West Germany on Berlin's 750th anniversary. In his speech, he challenged Mikhail Gorbachev to tear down the wall. So it was really because of Ronald Reagan's speech that the wall came down.
Speaking in front of the Berlin Wall at the Brandenburg Gate on June 12, 1987, Ronald Reagan called on Soviet leader Gorbachev: "Mr Gorbachev, open this gate! Mr Gorbachev, Tear down this wall!"