What the 1 µF / 25 V rating means for your board
The 25 V rating provides a solid derating margin against a 12 V or even 15 V rail — tantalum capacitors are sensitive to voltage spikes, so staying at 50% or less of rated voltage is a common reliability practice. The ±20% tolerance means the actual capacitance can range from 0.8 µF to 1.2 µF; for a bulk decoupling or RC timing application this is typical, but for a precision filter you would need a tighter tolerance part. The 8 Ohm ESR (equivalent series resistance) is relatively high for a 1 µF capacitor. At high frequencies the ESR dominates impedance, so this part is better suited for bulk storage or low-frequency filtering than for high-speed digital decoupling where you would want sub-ohm ESR. The molded construction gives it good mechanical stability and a low profile — 1.20 mm seated height — which matters in tight board stacks.
It can sit in an avionics black box, a downhole tool, or an outdoor telecom enclosure without derating for ambient temperature.