There are many types of uncertainty that economists have to deal with. Uncertainty in measurement of facts and figures (due to sampling or measurement error) - see Concepts: Facts and Figures. Uncertainty about an outcome or effect due to unknown states of the world. Uncertainty due to our lack of knowledge about behaviours or model assumptions.
Many economic variables, outcomes or effects will differ in different states of the world. See the way the Bank of England present CPI inflation projections (Bank of England Prospects for inflation).
The Bank of England also conveys this in the way it graphs GDP projections (Bank of England Prospects for inflation), which also convey uncertainty due to measurement.
The IFS shows uncertainty in individuals' responses to an increase in marginal income tax rates in a very straightforward way in Figure 3 of their analysis of the Labour Party Manifesto in the 2017 election.
