Original: If data is stored uncompressed, it takes more space but less time than if the data were stored compressed (since compressing the data reduces the amount of space it takes, but it takes time to run the compression algorithm).
Simplified: If data is stored uncompressed, it takes more space but less time than if the data were stored compressed (since compressing the data decreases the amount of space it takes, but it takes time to run the compression algorithm).