What Is A Bicameral Parliament?

A bicameral parliament is one which has two chambers, similar to the Uk, where there is the House of Commons and the House of Lords.  A unicameral parliament is one where there is only one chamber.  New Zealand, Sweden and Finland all have unicameral parliaments.
The UkK US and Australia all have upper houses.
Worldwide there are only abut 63 countries which have unicameral parliaments, with most countries preferring to have two houses.
This is a 'safety net' in case the lower house becomes too extreme.  Then the upper house can block anything.  This would be of benefit if a fascist government were appointed, then the upper house could keep a check on legislation.
However, the reality is that sometimes gridlock can occur.  In the United States opposing parties have controlled the Executive and Legislature for 25 out of the last 30 years.  Bill Clinto, a Democrat was widely opposed by the Repulican Congress.  This led to many government functions simply going inot 'meltdown' because they were unable to function.