Just some things that jump out at me:
You don't reset OnError
Huge red flag right there. If you're going to change OnError Goto you should immediately write the corresponding lines to set it back to normal.
Specifically:
On Error GoTo CurrencyTradesEmpty
CountCurrencyTrades = tblCurrencyTrades.DataBodyRange.Rows.Count
[On Error Goto 0]
CleanExit:
Exit Function
CurrencyTradesEmpty:
[On Error Goto 0]
CountCurrencyTrades = 0
Resume CleanExit
Your function has too many responsibilities
Single Responsibility Principle. Your function has a hardcoded worksheet, hardcoded listObject and then handles the counting of said object. I would have the function take a ListObject as an argument and let another function handle the retrieval of said objects. Like so:
Option Explicit
Public Function GetCurrencyTradesCount() As Long
Dim sheetCurrencyTable As Worksheet
Set sheetCurrencyTable = Worksheets("CurrencyTable")
Dim tblCurrencyTrades As ListObject
Set tblCurrencyTrades = sheetCurrencyTable.ListObjects("CurrencyQuery")
GetCurrencyTradesCount = CountListRows(tblCurrencyTrades)
End Function
Private Function CountListRows(ByRef targetList As ListObject) As Long
'/ On Error (I.E. empty list), returns 0
On Error GoTo CleanFail
CountListRows = targetList.DataBodyRange.Rows.Count
On Error GoTo 0
CleanExit:
Exit Function
CleanFail:
On Error GoTo 0
CountListRows = 0
Resume CleanExit
End Function
Scoping
Your function is implicitly public. You should explicitly set a Public or Private scope for it.
Integer
Is officially deprecated. The compiler will silently convert all Integers to Longs, so just use Long instead.
Error Handling
Do you really want your function to return 0 for all errors? What if it's given an empty object reference? I would rename your label to CleanFail: and think about what other failure scenarios it might want to deal with.