Buying time?

Yesterday, someone recommended me to buy aussie share. He said that is cheap. For long term, the market will be up again. He gave me the chart of ten years stock market. The market was up and down. But that is higher than ten years. I believe for long term, I can earn the money if I buy some share and sell ten years later. But Now, Cash is king.  I really don’t know which stock is good.