I assume that you are an Australian resident for tax purposes.
Disposing of shares, including foreign shares, is a CGT event which results in a capital gain or loss, and must be reported in your tax return. The capital gain is the proceeds of sale minus the reduced cost base of the shares. As the shares were held by an individual for more than a year, the CGT discount of 50% would normally apply.
To a first approximation, you would pay income tax at half your marginal rate on the sale proceeds, which would be about 17% of the amount received in your Australian bank account for the median full time worker.
If you're new to these concepts, it would probably be wise to consult an accountant. In particular, determining the cost base can be complex, and can significantly reduce the tax payable. It might also be wise to seek other deductions, such as from voluntary superannuation contributions, so that the one-off share sale doesn't push you into a higher tax bracket. An accountant can look at your previous tax returns and other personal information, and provide the most favourable calculation that the ATO will accept.