Sirach 14:17 states, "All flesh waxes old as a garment; For the covenant from the beginning is, You shall die the death." Let's break down the meaning:

"All flesh waxes old as a garment...": This is a simile, comparing human life to clothing. Garments wear out, fade, and eventually disintegrate. Similarly, all living things (flesh) age, deteriorate, and eventually cease to function. It's a recognition of the inevitable decline and fragility of human existence.

"...For the covenant from the beginning is, You shall die the death.": This refers to the idea that mortality is an inherent part of the human condition, ordained since the beginning. "The covenant" can be interpreted in a few ways:

The covenant with Adam (after the Fall): Traditionally, death entered the world as a consequence of Adam and Eve's disobedience in the Garden of Eden. This disobedience broke the perfect harmony and introduced mortality. So, "the covenant from the beginning" could refer to this altered state of existence after the Fall.
The natural order: Some understand this phrase to simply mean that death is a natural law of the universe. All living things are born, grow old, and die as part of the cycle of life. "The covenant from the beginning" is just another way of saying that mortality is inherent in the creation of living beings.
God's decree: It can also imply a divine decree, meaning that God has ordained that humans are mortal.

In summary, the verse emphasizes the inevitability of death as a natural part of the human condition. It's a poignant reminder of the fleeting nature of life, comparing it to a garment that wears out over time. It highlights that death is not a recent invention or an anomaly, but has been a fundamental aspect of human existence "from the beginning," whether understood as a consequence of sin or a natural law.

The verse encourages us to reflect on the value of our time and to live with wisdom, considering the brevity of life.