Capex is the cash version of what later becomes depreciation-accounting. Because it bypasses the income statement, a company can report strong ebitda while burning cash on equipment it must keep replacing.
Splitting it into maintenance-capex and growth capex is the analytical step that matters, though companies rarely disclose the split. A rough proxy is to treat depreciation as maintenance and the excess as growth.
Example: Northwind Tools spends $75M of capex against $64M of depreciation. Roughly $64M keeps the existing plant running and $11M funds a new assembly line, so growth capex is modest.
Related: maintenance-capex, free-cash-flow, property-plant-and-equipment, investing-cash-flow