What does it mean to be above reproach / blameless?

The dictionary defines reproach as "shame or disgrace or that which
brings rebuke or censure upon a person." The Bible speaks of being
"above reproach" or "blameless" as one of the distinctive marks of
those who aspire to the office of elder or deacon within the church (1
Timothy 3:2; Titus 1:6–7). Their work for the church, as well as their
interactions with others, are to be of such moral quality that they do
not bring shame or in any way disgrace the body of Christ or the name
of Jesus. This holds true not only within the church but outside it as
well.

The qualifications for the elder, sometimes called "overseer," and
deacon are outlined by the apostle Paul. He wrote, "Now the overseer
must be above reproach, the husband of but one wife, temperate,
self-controlled, respectable, hospitable, able to teach" (1 Timothy
3:2; cf. Titus 1:6–7). The word must is emphasizing that this
particular quality of being "above reproach" is an unconditional
prerequisite for a leadership role in the church.

Above reproach, however, does not mean without sin. No Christian lives
an entirely sinless life, nor will we until we reach the glorified
state in heaven. Above reproach means that the overseer's life is free
from sinful habits or behaviors that would impede his setting the
highest Christian standard and model for the church to emulate
(Hebrews 13:7; 1 Peter 5:3). Similarly, the overseer must not give
cause for those outside the church to impugn its reputation. Being
above reproach means that no one can honestly bring a charge or
accusation against him (Acts 25:7; 1 Peter 3:16).

In essence, the church's overseers must be men whose character is
unimpeachable, who are esteemed highly within their community. Such
men are known for their wholesome life and untarnished integrity.
Elders and deacons are to be men of good character and reputation.
Though Paul, in his letters to Timothy and Titus, is addressing the
distinguishing marks of those who desire to be church leaders, it
certainly does not diminish the need for all Christians to aspire to
the same qualities. Being above reproach should be an ongoing aim of
all believers (Colossians 3:7–10).